In the treatment of both animals and humans, it is often useful to provide a means for marking the site where a medicament is injected, inserted or otherwise applied.
More specifically, when dealing with animals which are being raised for food, it is often required that the animals be inoculated with a variety of materials in order to insure that the food harvested therefrom is wholesome. Furthermore, certain medicaments, albeit useful during the animal's growth phase, are nevertheless prohibited at the time of harvest. Regulations prescribe time limits regarding the use of such medicaments to insure a sufficient time period for clearing via natural biodegradation prior to harvest.
Industry compliance with the stated guidelines is a particularly vexing problem, which the industry has been recalcitrant in monitoring. For example, although feedlot attendants may be supplied with the required immunization or medicament, they may be derelict in their responsibilities and fail to apply the material to the animal.
Alternatively, a particular material might need to be given a clearing time period, for example 30 days prior to harvest, thereby allowing a safe clearing time from the animal's flesh. If the feed lot attendant is tardy in making the application, or simply becomes confused about the dates or inoculates a group of animals in error, harmful concentrations of the prohibited materials may find their way into the food supply.
With regard to human applications, there are instances where certain inoculations or tests are initiated and follow-up must occur at a prescribed time interval. In other instances, medicaments are provided in the form insertable implants which reside within the body for extended periods. Furthermore, in a military or possibly a hospital or nursing care environment, it might be beneficial to include a visual confirmation that an individual has received an inoculation.
In all of the above noted circumstances, the inclusion of a marking ingredient or tell-tale which has a controlled biodegradability can act as either evidence of instillation or evidence that a particular period of time has elapsed subsequent to instillation or application of the medicament.